Tibe deflation indicator



yMay 4, 1937. G. B. RQDNEY Re' 20,351

TIRE DEFLATION INDICATOR Original Filed Aug. 19, 1935 Gear 55165725? l Ressued May 4, 1937 UNITED STATES y Re. 20,351

TIRE nEFLA'rIoN mDICA'roR.

George B. Rodney, San Antonio, Tex. original No. 1,984,034, dated December 11, 1934,

Serial No. 685,889, August 19, 1933.

Application for reissue December 7, 1936, Serial No.

3 claims. (ci. zoo-5s) (Granted under the act of March 3, 1883, as amended April 3l), 1928; 370 O. G. 757) This invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a deflation indicator for pneumatic tired vehicles.

The principal object of the inventionis to provide an apparatus for notifying the operator of the vehicle of the deation of any tire below predetermined pressure.

Many automobile accidents are caused by the deation of a tire which so affects the control of the vehicle that it is practically impossible for the operator to hold the same on the road, It is not necessary that the deilation be instantaneous, as when a blow-out occurs, to cause a rapid skiddin'g from the road bed, since a side drag will develop from a slow leak, and may become disastrous if the car is travelling at a high rate of 20 speed. It is to prevent just such accidents that the applicant designed the apparatus which forms the subject matter of this application, for if the are indicated by like reference numerals-:1

Fig. 1 is a sectional view of the pressure switches showing the central stem in the position caused bydeilation of the tire;

Fig. 2 is a similar viewto Fig. 1 showing a slightly modified form adaptable 'to also indicate overination. In this gure the central stem is shown in a position corresponding to normal inflation of the tire.

The detail construction of the pressure switch,

particularly that type which functions only with deflation of the tire as shown in Fig. 1, will now be considered. This switch is composed ofl the following members:` An outer main stem (23) which is cylindrical in form and.` flanged at its lower extremity, the cylindrical portion is threaded externally for the reception of theadjustable metallic cap (24) andthe lock nut (25) for retaining cap (24) in any desired position.

ence for this purpose will be had to the accom-` panying drawing in which corresponding parts Slidably mounted within the main stem (23) is tted the plunger (26) which is made of brass or any other suitable -materiaL This plunger (26) is solid and of circular cross-.section and terminates at its lower extremity into a disc ('21) having a lower spherical surface (23) The exterior surface of plunger (26) and the upper surface of disk (21) are protected against short-circuiting contact with the main stem (33) by an` insulator (29) which consists of an insulating sleeve (50) and a disk (5l), of insulating material, the disk forming a lateral extension of the lowerend of the sleeve, as clearly shown in Fig. l of the drawing. The Yupper end of the central stem (26) is threaded for the reception of the adjustable contact nut (3D) and the internally threaded bushing (3|). The extension of the main stern ,(23) and the central stern disc (21) are enclosed by a rubber cover (32) in order to `protect the inner tube (33) of the tire (34) from coming in contact with, the metal parts..

The topof the adjustable cap (24) is drilled for the reception of a contact terminal (35) which is insulated from the cap by the insulator (36) comprising -a ilanged cylindrical member (31) and a centrally drilled disc (38).

Surrounding thel bushing (3l) and connected to the insulated terminal (35) and abutting the adjustable contact nut (30) is a helical spring (39) which tends to force the central plunger downward against the resistance of the air pressure in the inner tube of the tire. On deiiation of the tire the spring overcomes the decreased resistance and moves the plunger radially inward, until the adjustable contact nut (30) abuts the top of the main stem (23). Since the main stem (23) is grounded through the rim thev contact between the nut" (3011 and the main stem (23) establishes a circuit to the indicator, the current .passing through the spring (39), terminal (35),A

conductor( I 5) through other suitable conductors to the indicator located on the instrument panel.

switch to function and thus establishes a circuit to the particular signal device on the instrument board to indicate the location of the deflating The indicating instrument may consist of a battery of lights which are illuminated coincident with the deation of the tires. Thus if the right front tire deatesbelow a predetermined amount, say 20 pounds, a particular light will glow; the position oi the light determining the location of the -deiiating tire. Instead of a light 5 indicator, an electro-magnetically operated pointer indicator may be used o'r any convenient type suitable for location'. on the instrument board.

Setting the device for operation at any predetermined pressure is extremely simple; for example, suppose the normal pressure of the tires is thirty pounds, and it is desired that the signal operate when the tires are deflated to a pressure oi twenty pounds. AThe method of procedure is as l5 follows: Intlate all tires to a pressure of twenty pounds then screw down each of the caps (24) until the signal operates, lock the cap at this vheight by turning the lock nut (25) tight against the bottom of the cap and then proceed with the inflation of the tires up to the required thirty pounds of pressure. As soon as the tires are further inilatedthe operation of the signal will cease and it will not operate again until the tires are deilated to twenty pounds pressure.

Although the primary object of theV invention is'to indicate deation of any tire, -a modified form of the device may be constructed which will also indicate overinflation.- The'modiilcation consists in eliminating the extension (5l) from the cover (28) as shown in Fig. 2. When this extension is omitted overinilation causes the pressure within the tire tube (34) to -raise the plunger (26) until the top of the disc (21) touches the lower surface of the iianged extremity of the main stem (2l) making a circuit through the grounded main stem (2l) to the indicator, as'

described above.

It is obvious thatthose skilled in the art may vary the details of construction and arrangement of parts without departing from the scope -and spirit oi' the invention, and therefore it isnot desired to be limited to the foregoing de'- scription except as may be required by the claims. Having described myl invention, what I claim as new and wish tosecure by Letters Patent is: 1. A pressure responsive switch adapted to be mounted in the rim of an automobile wheel, said switch comprising anexternally threaded metallic main stem having one end extended through and clamped to the radial outward surface oi' said rim, a central plunger comprising a stem threaded at its upper extremity for the reception of a contact `nut,.said contact nut having a flanged extremity adapted to serve as an electrical contact surface in conjunction with the upper extremity of the main stem, a cylindricalv insulating sheath surrounding the unthreaded ,portion oi the plunger stem and slidably mounted within said main stem, the stem of the plunger terminating at its lower end in a disc, insulating means extendingl from the lower end of the sheath and t overlying saiddisc to insulate the upper suraosi i face of said disc against short-.circuiting contact with the main stem, a cap adjustably tted to the main stem, means for retaining said cap in any predetermined position along said stem and a spring interposed between the ilange oi th contact nut and the top of the cap, and an insulated terminal fitted in the` top oi! said cap and connected to said spring.

2. A pressure responsive switch adapted to be mounted in the rim of an automobile wheel, said switch comprising an externally threaded metallic main stem having oneend extended through an opening in the rim, s'aid end being clamped to the radially outward surface of said rim, a central plunger slidably mounted within the main stem and including a stem threaded at its upper extremity for the reception of a contact nut, said contact nut having a ilanged extremity adapted to serve as an electrical contact surface in conjunction with the upper extremity of the main stem, a cylindrical insulating sheath surround-l ing vthe unthreaded portion of the plunger s tem and slidably mounted within said main stern, the stem ofl the plunger terminating at its lower end in a disc of greater diameter than the insulating sheath; the upper surface of said disc and the adjacent surface of the main stem serving as electo the mainy stem and means for retaining said cap in any predetermined position along said stem, a spring interposed between the ilange of' the contact 'nut and the top of the cap to react against the plunger, the compressive resistance of said spring depending onthe adjustment of the capA andan insulated terminal iltted in the' top oi said ycap and connected to said spring.

3. A pressure responsive switch adapted to be mounted in the rim of an automobile, said switch comprising an externally threaded stem. having lplunger member, a cap internally threaded for engagement with said stem,.means in connection Atrical contact surfaces, a cap adjustably fitted with the stem and coacting with the cap whereby threaded engagement of the cap with the stem is restricted to a point on the latter determined withfreference to a selected ination pressure, a spring interposed between the con-l tact nut on the plunger member and the top oi' said cap.- and an insulated `terminal fitted in the top oi.' the cap and connected to said spring.

- GEORGE B. RODNEY. 

